Battery wiring - This looks wrong
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Topic: Battery wiring - This looks wrong
Posted By: Luv2Q
Subject: Battery wiring - This looks wrong
Date Posted: 26 Oct 2014 at 9:05pm
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Here's the way our two 12s were wired (in parallel) as delivered. What looks wrong to me is that the (+) and (-) to the trailer are both coming off the same battery. I would have thought the (+) should come off one battery and the (-) should come off the other. I'm thinking I've seen something to this effect in a previous post (maybe by CharlieM?) This way seems to work ok but is it the "correct" way? Next question: With the two batteries wired in parallel, do I need a separate battery disconnect for each battery? Sure will appreciate some informed opinions.  ------------- John & Teri Tundra 5.7L V8 / RP 180 E2 WDH / Integrated controller (POS) replaced by Tekonsha P3 |
Replies:
Posted By: dsmiths
Date Posted: 26 Oct 2014 at 10:46pm
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No that is correct, when the batteries are in parallel the voltage is the same 12 volts, but the current is doubled. you can do a battery disconnect by disconnecting the positive wire that feeds the pod. ------------- Dane and Donna Smith 2011 RP-172 2008 Chevrolet Trailblazer 4X4 lift kit prodigy wireless brake controller |
Posted By: techntrek
Date Posted: 27 Oct 2014 at 8:46am
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Technically they are wired correctly because they will give you 12 volts, with double the amperage. However, you are right that they should not be connected that way, and should be connected with the (+) on one and the (-) on another. The resistance in those black wires, however minimal, will still be enough to prevent the battery on the left from charging fully, or discharging as much as the one on the right. Eventually the right one will fail before the left one.
See the 2nd diagram on this page: http://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel/ - http://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel/ ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual 
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Posted By: Luv2Q
Date Posted: 27 Oct 2014 at 10:41am
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Thanks, Dane & Doug. Makes sense. On disconnecting between trips, should both positives (or both negs) be disconnected? I read somewhere that this prevents discharging one battery thru the other. Or is this now fine-tuning battery maintenance beyond what's really necessary? Thanks again, gents. This sure is helpful. ------------- John & Teri Tundra 5.7L V8 / RP 180 E2 WDH / Integrated controller (POS) replaced by Tekonsha P3 |
Posted By: techntrek
Date Posted: 27 Oct 2014 at 11:30am
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You only need to worry about the connection to the pod. In your case you have 3 positive and 3 negative connections, I assume due to an electric tongue jack. You can leave the one that runs to the other battery. You could even leave the one to the tongue jack, since it doesn't have any "phantom load" when not in use. There's an outside chance its switch could fail so that is your call. Personally if you are adding a disconnect switch or fuse there isn't any extra work to include the tongue jack connection so I would. The most important one to disconnect between trips is the heavier red wire which runs to the converter and then to the rest of the loads in the pod. The LPG detector and fridge control board both use power and will kill the battery in a week or two if you don't. Reconnect the battery to the pod, and then connect the pod overnight, at least every 30 days. Also before and after any trip. ------------- Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual
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Posted By: furpod
Date Posted: 27 Oct 2014 at 11:35am
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ALL my EE friends tell me that there is no functional issue with having them that way. If it was a larger battery bank, possibly a problem, but with just 2 12v's, 4 out of 4 say the lifetime "damage" done by having two batteries wired like that will not be measurable.
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Posted By: JStrube
Date Posted: 29 Oct 2014 at 5:51pm
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That is how mine are wired, also how my Diesel F250's batteries came wired from Ford. ------------- 2012 181G |
Posted By: Luv2Q
Date Posted: 30 Oct 2014 at 5:53am
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Doug, Mark, John: thanks for sharing your observations. Much appreciated, I assure you. My take-away from the discussion:
Thanks again, y'all. ------------- John & Teri Tundra 5.7L V8 / RP 180 E2 WDH / Integrated controller (POS) replaced by Tekonsha P3 |
Posted By: Podster
Date Posted: 30 Oct 2014 at 11:07am
Agreed, it is an issue of balance and efficiency. ------------- Cliff & Raelynn Ranger 4.0/178 (1/2 ton 5,800lb tow capacity) |